In typical AC power generation systems, a frequency of a generated AC power signal is dependent on a rotational frequency of a rotor of the power generation system. Likewise, in a multiphase AC power generation system the frequency of each phase of a power signal is dependent on the rotational frequency of the rotor.
Independent speed variable frequency (ISVF) generators enable generation of an AC electrical power signal having a frequency that is independent of a rotor speed. In order to achieve an independent frequency, an AC power signal generated during a pilot stage may be transmitted back to a rotor of the ISVF generator. The power may then be modulated and used to generate a second magnetic flux at the rotor that rotates relative to the rotor. The second magnetic flux may be used to generate a main machine stage power signal for distribution. The frequency of the main machine stage power signal may depend on both the rotational frequency of the rotor and on the rotational frequency of the second magnetic flux. As such, the frequency is independent of the rotational frequency of the rotor alone. ISVF generators also enable control of other parameter of the main machine stage power signal, such magnitude and phase.
The inclusion of a modulation stage, such as rectifying circuitry, inverter circuitry, or other circuitry, on a rotor of a generator may add to the costs associated with the design and manufacturing of an independent speed variable frequency generator apparatus. Further, the strong rotational forces on the rotor may result in a lower life span of electrical components used to implement the rectifying circuitry and inverter circuitry. Other disadvantages may exist.